Question

Mario is 63 years older than his grandson Jonas. How many years ago was Mario's age 10 times Jonas's age if Mario's age is currently four times Jonas's age?

Answer 1

Answer:

14 years ago

Explanation:

Let Mario's age be m, Jonas age be j.

From, Mario is 63 years older than Jonas

Equation 1: m = j + 63

From, Mario's age is four times Jonas age

Equation 2: m = 4j

Solve them by substitution:

m = j + 63

4j = j + 63

4j - j = 63

3j = 63

j = 21

Find Mario's age:

m = j + 63

m = 21 + 63

m = 84

Follow this steps:

m - y = 10(j - y)

84 - y = 10(21 - y)

84 - y = 210 - 10y

-y + 10y = 210 - 84

9y = 126

y = 14

Answer 2

The answer is 14 years ago.

Let Mario's age be M, and Jonas' age be J.

The formed equations :

1. M = J + 63
2. M = 4J

To find their current ages, substitute the 2nd equation in the 1st equation.

4J = J + 63

3J = 63

J = 21

M = 4(21)

M = 84

For Mario to be 10 times Jonas' age, he has to be an age that is a multiple of 10.

Case (1) : Mario's age = 80

Subtract 4 from both their ages.

Mario : 84 - 4 = 80

Jonas : 21 - 4 = 17

17 × 10 ≠ 80

Case (2) : Mario's age = 70

Subtract 14 from both their ages.

Mario : 84 - 14 = 70

Jonas : 21 - 14 = 7

7 × 10 = 70